Dr. Merjaneh is a pediatric endocrinologist at Seattle Children’s and associate professor of pediatrics at the University of Washington.

Q: What are the most common causes of short stature in children?

Although slower-than-normal growth may be a sign of a health problem, most children who have short stature have no medical condition, are healthy, and grow at a normal rate.

The most common causes of short stature in children are familial short stature (one or both parents are short, but the child’s rate of growth is normal and the bone age is normal) and constitutional delay of growth and puberty (the child is short during most of the childhood but will have late puberty and end up with normal adult height. There is usually a family history of constitutional delay, and the bone age is mildly delayed). Both conditions are benign and do not require an intervention.

Less commonly, short stature can be pathologic due to a medical condition. Endocrine causes of short stature include growth hormone deficiency, hypothyroidism, and Cushing disease. Chronic medical conditions such as heart disease, celiac disease, inflammatory bowel disease and kidney and blood disorders can be associated with short stature. Short stature is also found in many genetic conditions such as Down syndrome and Turner syndrome and is usually associated with features suggestive of an underlying condition. Additionally, poor nutrition can result in poor growth that improves with the advancement of nutrition and weight. Finally, being born small for gestational age without catching up on growth can result in short stature in childhood.

Q: What is the best predictor of adult height?

Genetic potential is the best predictor of final adult height. We use mid-parental height, a calculation that includes both parents’ heights, as a rough estimate of adult height. It is calculated in centimeters as follows: for boys: (Father’s Height + Mother’s Height + 13) / 2. For girls, it is (Father’s Height – 13 + Mother’s Height) / 2.

Q: When should PCPs get concerned about short stature and refer to endocrinology?

We would like to see children with short stature if their height is below the third percentile (with normal parents’ heights), if their growth velocity is slow (less than 4 cm per year) or if their height is greater than or equal to 3 standard deviations below expected height based on mid-parental height. This information is available on our website under the Short Stature Referral Algorithm. We recommend you start the workup for short stature before you refer the child to us. The workup includes a bone age in addition to blood testing to screen for growth hormone deficiency, thyroid disease, celiac disease, blood disorders and kidney disease. This information is included in the algorithm.

Q: Are there instances when referral to Endocrinology for short stature is not helpful or needed?

If the child has completed growth, there is not much we can offer, and there is no need to refer. This is easy to assess by obtaining a bone age. Growth is complete if the bone age is 16 years or more in males or 14 years or more in females. Additionally, if short stature is familial in etiology or due to constitutional delay, then no referral is needed, as no intervention is indicated. Finally, if the child has failure to thrive with low BMI or weight/height percentile, then a referral to Nutrition and/or Gastroenterology is more appropriate since hormonal causes of short stature are usually associated with normal or high BMI or weight/height percentile.

Q: Is there a role for nutrition, vitamins or dietary supplements in improving height outcome in non-pathologic short stature?

No, vitamins or dietary supplements do not improve height outcomes in a child with normal weight. They are only helpful in cases of poor nutrition and low weight.

Q: When do you suspect and how do you make the diagnosis of growth hormone deficiency?

We suspect growth hormone deficiency when the child’s height is shorter than what would be expected for their mid-parental height with a normal weight and the growth rate is slower than normal over a period of at least 6 to 12 months. Additional history findings that raise suspicion for growth hormone deficiency include the presence of midline defects or CNS malformations, micropenis and history of neonatal jaundice or hypoglycemia.  We start screening by obtaining growth hormone factors, including IGF-1 and IGFBP-3. Measuring a random growth hormone level is not helpful because it is secreted in a pulsatile fashion. If the growth hormone factors are low, then we proceed with growth hormone stimulation testing. This test involves using two different medications that stimulate growth hormone secretion and measuring multiple growth hormone levels over two to three hours. If growth hormone deficiency is confirmed, a pituitary MRI is done to evaluate for pituitary pathologies before starting growth hormone treatment.

Q: When do you offer growth hormone treatment for children with short stature?

Growth hormone has specific FDA-approved indications for use in short stature. These include growth hormone deficiency, Turner syndrome, Prader-Willi syndrome, Noonan syndrome, chronic renal failure, being born small for gestational age with lack of catch-up growth by age 2 years and idiopathic short stature.

Idiopathic short stature is short stature with no identifiable etiology in an otherwise healthy child. Height is more than 2.25 standard deviations below the mean for sex and age, and bone age is normal, predicting a short adult height.

Q: Is growth hormone therapy safe? What are the risks and side effects of this treatment?

Growth hormone is generally safe when used within its FDA-approved indications. The common side effects include lower extremity pain (similar to growing pains), gynecomastia, worsening of preexisting scoliosis and worsening of adenotonsillar hypertrophy. Rare but severe side effects include pseudotumor cerebri, slipped capital femoral epiphysis (SCFE), worsening insulin resistance and diabetes.

Q: What final advice would you like to offer PCPs regarding short stature?

When evaluating a child for short stature, it is important to first rule out measurement errors and inaccurate plotting. It is also important to calculate mid-parental height to assess if the child is appropriate for their genetic potential. Weight and BMI should also be assessed, and if underweight for height, poor nutrition or a systemic illness are more likely than an endocrine disorder. Finally, please refer to our Short Stature Referral Algorithm when considering a referral to Endocrinology for short stature. The algorithm can help you decide if the referral is appropriate and can guide the workup needed prior to referral.